Improvements in three-dimensional accelerometers have been instrumental in increasing the acceptance of personal activity tracking devices (ATs). ATs can measure movement of the wearer and are able to detect and record physical activity such as walking, running and exercising. Some ATs have the capability of detecting other biometric characteristics such as heart rate. ATs also may be equipped with connection means including but not limited to Bluetooth, Ethernet, USB, WiFi, and IrDA and are used to connect with a mobile phone running application software or to a server connected with the cloud. Use of the ATs allows a user to enter fitness goals such as goal of how many steps to walk over a predetermined time (e.g., day, week, month), how many hours to sleep over a predetermined time (e.g., 24 hours, 48 hours, week), and quality of sleep based on combination of sleep time and movement detected while sleeping (periods of restlessness).